It is well-known that the earth's magnetic field varies with the location of measurement in different parts of the world. Because of these variations, it is difficult, if not impossible, to employ standard compasses universally without first making time-consuming and intricate modifications of these instruments. Specifically, because of the vertical component of the earth's magnetic field, a compass needle which is horizontally balanced at one location on earth can dip from the horizontal plane at another location. Such dipping can cause severe inaccuracy or inoperability of the instrument. A common practice to overcome this unwanted condition has been to add weight, generally in the form of a coiled wire, to one arm of the compass needle to return the entire needle to a generally horizontal plane. To accomplish this, however, a user must break the integrity of the compass housing and most carefully add weight to the delicate needle. Such activity is inconvenient, time-consuming, possibly inaccurate, and, if damage to the instrument occurs, costly.
In U.S. Pat. No. 4,175,333, owned by the assignee of the instant application, a compass is disclosed wherein dip or tipping of the direction pointer is compensated for to some extent by offsetting the pointer arms beneath the pivot point. Such positioning enables the earth's magnetic and gravitational forces, in relation to the pivot point, to be optimally forceful in a manner much like that of the center of gravity in general balance considerations thereby enhancing horizontal plane maintenance of the pointer arm.
The compass which is the subject of the instant invention provides automatic compensation for tipping of the pointer through counterbalancing of the magnetic forces in relation to the earth's magnetic force, resulting in an instrument wherein the pointer remains in a generally horizontal plane irrespective of geographical location. The instant invention additionally overcomes effective dampening and vibration problems associated with unwanted pointer movement during directional reading and recordation.